Quote:
Originally Posted by Stl-986
How is changing tire & wheel sizing going to let the engine make or lose HP? Have Dyno numbers to show it? An engine is going to make the exact same HP rather it has 12" wheels or 30" wheels. If smaller wheels/tires made more HP then every supercar ever made would come with the smallest wheels possible.
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Engine does not produce more power, but less rotational mass reduces power loss so effectively more power to move the car.
Simple math is every 1 pound of rotational mass reduction equals 7 lbs static weight reduction, and I figure 100 lbs static weight loss is like 10 hp gain. I’m going after weight reduction, with a 5-lb lithium iron battery, etc.
Same with the underdrive pulley, it does not make the engine produce more hp but reduce parasitic loss from belt-driven engine accessories, which effectively helps the car accelerates faster. I did feel a bit more get up and go.
It’s a simple physics, and dyno does not measure how fast the car goes anyway.
For racing they change gear ratios for the same effect… and many other reasons to keep the tire size as large as it is….